CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION ANALYSIS OF THE 190-ANGSTROM-LONG COILED-COIL DIMERIZATION DOMAIN OF THE ACTIN-BUNDLING PROTEIN CORTEXILLIN-I FROM DICTYOSTELIUM-DISCOIDEUM

We have crystallized the similar to 190-Angstrom-long parallel two-str anded coiled-coil oligomerization domain of the actin-bundling protein cortexillin I from Dictyostelium discoideum. The orthorhombic crystal s belong to the space group C222(1) with unit cell dimensions of a = 7 1.3 Angstrom, b = 127.8 Angstrom, and c = 91.6 Angstrom. As both nativ e and selenomethionine-substituted protein crystals diffract to 3.0 an d 2.85 Angstrom resolution, respectively, using synchrotron radiation, they are suitable for the first high-resolution structural analysis o f a two stranded coiled coil comprising more than six heptad repeats. Moreover, because the polypeptide chain fragment contains a recently i dentified two-heptad-repeat long sequence that is indispensable for th e assembly of the cortexillin I coiled-coil oligomerization domain, it s high-resolution structure should enable us to extend our knowledge o n the molecular mechanisms underlaying coiled-coil formation and to es tablish the precise manner in which the two ''trigger'' sequences inte ract with one another in the dimer. (C) 1998 Academic Press.